<div dir="auto">A general comment about convergence, as there have been a few recent questions.<div dir="auto"><br></div><div dir="auto">Convergence is similar to paddling a canoe down a river from the mountains to the sea. Sometimes the water is rushing by and you (the mixer) have to try and avoid the rocks (ghost bands); sometimes you go over a waterfall and the problem changes (electronic phase transition); sometimes you are on a meandering river and do not seem to be making progress.</div><div dir="auto"><br></div><div dir="auto">Check-mixing is designed to give some idea about what is going on, as a simple grep on :DIS, for instance, does not reveal enough.<br><br><div data-smartmail="gmail_signature" dir="auto">_____<br>Professor Laurence Marks<br>"Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi<br><a href="http://www.numis.northwestern.edu">www.numis.northwestern.edu</a></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Nov 26, 2019, 07:21 Luigi Maduro - TNW <<a href="mailto:L.A.Maduro@tudelft.nl">L.A.Maduro@tudelft.nl</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span lang="EN-GB">Hello there WIEN2k users,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">I am having a convergence problem with a supercell calculation of a slab of MoS2 including Spin-Orbit Coupling (SOC). The supercell is made by cutting in the plane of MoS2 which leads to either only edge Mo atoms or edge
S atoms. A vacuum parallel to the edges is introduced (about 18 angstroms) that separates the repeating images. Converged SCF calculations without SOC were found with this type of geometry for various widths. These converged SCF calculations were then used
as input for an SCF calculation with SOC for the different widths. However, when including SOC only the smallest width gave a converged SCF calculation, albeit after doubling the amount of k-points and increasing nbands(more than twice what was originally
suggested when running init_so). The larger widths do not result in a converged SCF calculation, even after substantially increasing nbands. Is the solution to just keep on increasing the amount of k-points until I do get converged SCF calculations or is the
inclusion of the vacuum giving problems for lapwso?<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">As a side not, I have a general question on how to relate Emax and nbands in case.in1. Up until recently I have been using SCALAPACK in WIEN2k and now I have switched to using ELPA. In the case of MoS2, a system with
large spin-orbit coupling, the userguide recommends to increase the value of Emax to up to 10 Ry for large SOC systems when running the init_so script. If one is using ELPA then nbands should be increased. In the case of ELPA should nbands be increased to
twice the amount given in case.in1 when initially running init_so? <u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">PhD candidate<br>
Kavli Institute of Nanoscience<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Department of Quantum Nanoscience<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Faculty of Applied Sciences<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Delft University of Technology<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
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